SBIR Phase I: High Capacity Li2S-Si Rechargeable Batteries for Energy Storage Applications

This Small Business Innovation Research Phase I project will develop a novel secondary battery platform based on a lithium sulfide-carbon composite cathode and a silicon anode that demonstrates high energy density and long cycle life. Today, mobile devices require faster performance and smaller sizes for greater portability. However, the faster processors in these devices impose energy density requirements that push today's lithium battery technologies to their limits. Li2S/Si configuration offers the highest theoretical specific energy (1.55 kWh/kg) based on the lithium-ion battery platform and furthermore is not subject to the safety issues related to other secondary lithium battery systems which employ metallic lithium. The development of the Li2S/Si battery has been hindered by the limited cycle life of the cathode and the anode. On the cathode side the company has developed methods of creating porous carbon hosts for sequestering sulfur and on the anode side methods of synthesizing Si nanowires to prevent pulverization, hence obtaining stable performance for both electrodes. In the Phase I Project the company will optimize performance of their electrodes and develop scalable processes for production. This research will result in continued performance improvement of the Li2S/Si platform and identify critical processing techniques and challenges for scale-up. The broader impact/commercial potential of this project is that it is able to bring about significant changes to the rechargeable lithium battery technologies and the market because of their approximately three fold energy density advantage over the current chemistry platforms (0.2-0.6 kWh/kg). Lithium-ion batteries (LIB) currently have a market of $11-13 billion and the sales are expected to increase to at least $40 billion by 2020. LIBs are widely employed in portable electronics and are expected to be the driving force for development of the new generation of hybrid and electric vehicles. If the proposed technology can be brought to commercialization, the improved performance characteristics such as higher energy density, higher power and longer cycle life will allow manufacturers/consumers to power their devices/vehicles for longer periods of time and gain performance advantages in their respective applications.